We often hear about the benefit of BCAAs for building muscle and supporting recovery from strength training, but can BCAAs improve endurance performance?
Are BCAAs helpful for marathon runners, triathletes, or other endurance athletes?
Keep reading to learn about whether BCAAs increase endurance exercise performance.
Do BCAAs Increase Endurance?
Endurance athletes often focus on carbohydrate fueling before and during long workouts, but there is evidence to suggest that BCAAs may increase endurance exercise performance.
Here are some of the benefits of BCAAs for endurance athletes:
BCAAs conserve glycogen
Glycogen, which is the storage form of carbohydrates in the body, is the preferred fuel source for the muscles during high-intensity exercise, including marathon running, long-distance cycling, and triathlons.
The reason that the percentage of energy coming from carbohydrates is greater than the percentage of energy coming from fat during vigorous exercise is that glucose and glycogen can be used to produce ATP (energy) faster than stored fat.
The muscles need a steady supply of large amounts of ATP quickly when running or exercising at a vigorous intensity for a continuous bout.
Fat oxidation takes too long to yield ATP if you are trying to sustain high-intensity efforts over a prolonged time.
However, the downside of using glucose and glycogen during endurance exercise is that the glycogen storage in the body (where it is mainly found in the muscles and liver) is limited.
Marathon runners and other endurance athletes try to preserve glycogen storage during long runs and races by supplementing with energy, gels, sports drinks, and other forms of carbohydrate fuel.
Unfortunately, it is typically impossible to supplement with enough carbohydrates during vigorous exercise that lasts two, three, or four hours or more.
Trying to ingest too much fuel (sugar) can cause digestive issues and absorption and utilization rates are also finite.
Therefore, the body can run out of ample glycogen or readily available carbohydrates to burn.
Then, the athlete is relegated to using stored fat (triglycerides).
This results in a forced and unintentional reduction in intensity or slowing down your pace because the energy production from fat can’t keep up with the energy demand from the muscles.
If you have ever run a marathon or done some sort of long-distance race or long workout, you may have experienced the dreaded feeling of “hitting the wall“ or “bonking.”
This feeling—a sudden shift from feeling strong and fast to sluggish, heavy, and slow—is the sign that you have depleted your glycogen stores, and the muscles are now relying on fat oxidation to produce ATP.
One study found that supplementing with BCAAs during endurance exercise helped preserve glycogen stores, delaying the metabolic shift to fats and the resultant performance decline.
The unique branched-chain structure of BCAAs allows these amino acids to be broken down quickly and utilized for energy, bypassing the normal digestive process for proteins.
BCAAs can be taken up by muscle cells directly and used to create ATP instead of carbohydrates.
Therefore, supplementing with BCAAs during prolonged exercise (alongside carbohydrate supplementation) can help preserve muscle and liver glycogen stores longer than just supplementing with simple carbohydrates or not taking in any fuel.
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BCAAs may reduce muscle damage in endurance athletes
One study found that supplementing with BCAAs during endurance exercise helped minimize muscle damage.
This may help reduce delayed-onset muscle soreness (DOMS), which is the achiness, stiffness, and soreness that develops in the 24 hours after intense exercise and may last 2-3 days.
It may also facilitate faster recovery.
This would enable endurance athletes to bounce back faster after marathons or long workouts.
BCAAs may reduce perceived exertion
Another potential benefit of BCAA supplements for endurance athletes is the potential reduction of central fatigue.
Central fatigue is a multi-faceted phenomenon involving the central nervous system.
It can cause symptoms of both physical and mental exhaustion during prolonged exercise.
BCAAs have been shown to play a role in delaying or preventing central fatigue by affecting the neurotransmitters that partially contribute to this problem.
For example, BCAAs may reduce serotonin production, and high levels of serotonin may lead to real or perceived feelings of exhaustion.
This would allow you to feel mentally and physically strong during endurance events.
How to Take BCAAs to Improve Endurance
Most of the research surrounding the benefits of BCAAs for endurance exercise has found that you have to consume BCAAs during the workout or competition to reap the benefits.
Only using BCAA supplements before exercise or in a post-workout meal or snack will not offer the same benefits.
In order for BCAAs to be used as fuel to preserve glycogen during endurance exercise, the body has to have a steady intake of branched-chain amino acids concurrent with the physical activity.
To date, there is still limited research on the optimal dosage and timing of BCAA supplements during endurance workouts.
Most sports nutritionists recommend that to maximize the benefits of BCAAs for endurance exercise, it is better to provide a continuous supply throughout the workout at relatively lower doses than sporadically or less frequently in high doses.
For example, instead of ingesting 5 grams of BCAAs once—let’s say 90 minutes into a projected three-hour marathon finish—it is better to take 1 gram of BCAAs with your carbohydrates every 20-30 minutes throughout the race from the start.
Consider working with a sports nutritionist and experimenting on your own to find the optimal timing and dosage of BCAAs during long workouts for your body.
Factors such as your overall diet, fueling strategy, training status, body size, sex, and running pace/exercise intensity will all impact the best strategy for BCAAs during marathon training or other endurance activities.
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